GB2046469A - Zoom lens system having a close focus facility - Google Patents

Description

1 This invention relates to a zoom lens system of the "two-hand" type,

i.e. having separate focussing and zooming rings, which is operable selectively in normal focussing and close-focussing modes.

Various constructions of two-hand type zoom lens systems are known in which a close-focussing or 11 macro" mode is obtained by continuous rotation of the zooming ring. Typically, close-focussing opera tion is provided as a continuation of the zooming operation without any specific change-over, orthe zooming ring is rotated into a close-focussing region by operation of a change-over mechanism. Since, however, change-over into the close-focussing mode can be performed irrespective of the rotational position of the zooming ring, two kinds of operation al rings must be variously combined so as to obtain optimum photographic magnification. This is very troublesome both constructionally and operation ally.

It is an object of the present invention to obviate or 90 mitigate this problem.

According to the present invention, there is pro vided a zoom lens system operable in a normal focussing mode and a close-focussing mode, com prising a focussing ring rotatable to effectfocussing of the lens system in the normal focussing mode, a zooming ring rotatable independently of the focus sing ring to alterthe focal length of the lens system in the normal focussing mode and to effect close focussing of the lens system in the close-focussing mode, and a change-over control operable to change the lens system between its normal focussing and close-focussing modes only when the focussing ring and the zooming ring are both in respective prede termined positions, operation of the control into the close-focussing mode rendering the focussing ring inoperative.

Preferably, operation of the change-over control into the close-focussing mode locks the focussing ring against rotaton relative to a fixed mount of the lens system.

The zoom lens system can comprise two, three or four lens groups. The term "lens group" is used herein to denote one or more lenses whose relative positions are fixed and which move together during focussing or zooming.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a cross-sectional view of a first 120 embodiment of a zoom lens system according to the present invention, illustrating zooming of the lens system in a normal focussing mode; Figure 2 is a similar view to Figure 1, but illustrating focussing of the lens system in a closefocussing mode; Figure 3 to 7 are developed side views of the first embodiment of the lens system at various stages in its operation; Figure 8 is a cross-sectional view of a second 130 SPECIFICATION

Macro photographing change-over device for zoom lens GB 2 046 469 A 1 embodiment of a zoom lens system according to the present invention, illustrating zooming of the lens system in a normal focussing mode; Figure 9 is a similar viewto Figure 8, but illustrating focussing of the lens system in a closefocussing mode; Figure 10 is a cross-sectional view of a third embodiment of a zoom lens system according to the present invention, illustrating zooming of the lens system in a normal focussing mode; Figure 11 is a similar view to Figure 10, but illustrating focussing of the lens system in a closefocussing mode; and Figures 12 and 13 are partial cross-sectional views showing respective modifications which can be made to the zoom lens system shown in Figures 1 to 7.

Referring first to Figures 1 and 2, the zoom lens system depicted therein is composed and three lens groups Ll, Lil and Llll. During zooming, the first lens group Ll is moved integrally with the third lens group Llll while the second lens group Lil is moved relative thereto. For normal focussing operation, only the first lens group Ll is moved while the second and third lens groups Lil, Lill remain stationary. For close-focussing, the lens system is set to its maximum focal length and its minimum force, and only the second lens group Lil is moved.

The upper half of Figure 1 shows the zoom lens system set at its minimum focal length and focussed on infinity. The lower half of this Figure shows the lens system set to its maximum focal length and still focussed on infinity. The upper half of Figure 2 shows the lens system set at its maximum focal length and at its minimum focussing distance, while the lower half of this Figure shows the lens system in a close-up or macro photographing position.

Afocussing ring or barrel supports the first lens group L, and has thereon a helicoid screwthread la which is used in the focussing operation and a guide groove 1 b for transmission of angular movement during the focussing operation. Reference numeral 2 designates a first moving sleeve or barrel which supports the second lens group Lil and to which a guide pin 12 for transmitting the movement of the second lens group is connected. A second moving sleeve or barrel 3 supports the third lens group 1-111 and has a helicoid screw thread 3b which meshes with the helicoid screw thread la, the first moving barrel 2 being slidingly supported on the second moving barrel 2. A second guide pin 13 for transmitting the movement of the first and third lens group Ll and Lill is rigidly coupled to the second moving barrel 3. A guide groove 3a (see Figures 3 to 7) in the second moving barrel 3 receives the guide pin 12 therein and defines the path of rotational movement of the first moving barrel 2 about the optical axis while at the same time guiding the movement thereof in the direction of the optical axis. A guide groove 3c defines the range of focussing while guide grooves 3d and 3e define the zooming range of the lens system.

A fixed mount barrel 4 is provided with a mount portion for attachment to or detachment from a camera body (not shown). The mount barrel 4 2 GB 2 046 469 A 2 supports the second moving barrel 3 slidably and has a guide groove 4a therein in which the guide pin 13 is inserted, the guide groove 4a defining the path of rotational movement of the second moving barrel 3 around the optical axis and at the same time guiding the second moving barrel 3 in the direction of the optical axis. Also provided in the mount barrel 4 is a guide groove 0 in which the guide pin 12 moves and which is operated in the same manner as the guide groove 4a. A cam sleeve 5 is slidingly supported by the mount barrel 4 and has rigidly coupled thereto a guide pin 11 which transmits its rotational movement and a guide pin 14 which receives rotational movement. Grooves 5a and 5cfor imparting relative movement to the respective lens groups during zooming and grooves 5b and 5dfor imparting relative movement to the respective lens groups during close-focussing are formed in the cam sleeve 5, as shown in Figures 3 to 7. A guide ring 6 is slidingly supported by the second moving barrel 3 and has rigidly affixed thereto a guide pin 9 which is slidingly disposed in the grooves lb and 3c. A change-over groove 6a, the position of which varies in accordance with the focus condition of the lens system during normal focussing, is formed in the guide ring 6 for determining when change-over is possible into and out of the close- focussing mode.

A change-over sleeve 7 is slidingly supported by the second moving barrel and has rigidly coupled thereto a guide pin 10 which is slidingly disposed in the guide grooves 3d and 3e. In the normal focussing mode, angular movement of the cam ring 5 is transmitted to the change-over sleeve 7 through a guide groove 7c in the latter and the aforementioned guide pin 11. Also provided on the change-over sleeve 7 are a projection 7a which produces an indication for enabling change-over from the zooming or normal focussing mode to the close-focussing mode and a projection 7b which indicates the position where change-over from the closefocussing mode to the normal focussing mode is possible.

In the embodiment shown, such change-over can be effected with the lens system set to its minimum focussing distance and its maximum focal length. Therefore, the groove 6a and the projection 7a become mutually aligned only when the focussing sleeve 1 is rotated to the minimum focussing distance and a zooming barrel 8 is rotated to the maximum focal length position.

The zooming and close-focussing operations are both controlled by the zooming barrel 8, in which a guide groove Sa for defining the movement of the cam sleeve 5 in the direction of the optical axis is formed. The guide pin 14 coupled to the cam sleeve 5 is slidingly engaged in the guide groove 8a. With this construction, the zooming barrel 8 is rotated integrally with the cam sleeve 5. The zooming barrel 8 is co- axially supported by engagement of a screw thread 8b thereof with a screw thread 4c of the mount barrel 4.

An alternative construction may be used in which the zooming barrel 8 is supported by the mount barrel 4 so as to be rotatable freely around the optical axis without any movement thereof in the direction of the optical axis, as shown in Figure 13. Moreover, if the movement of the cam sleeve 5 and the zooming barrel 8 in the direction of the optical axis are defined or controlled and both members are rotatablay supported freely by the screw threads 4c and 8b, the following effects are obtained. With reference to Figure 12, the zooming barrel 8 is divided into a zooming operational barrel 8'having a guide groove 8a and a ring member 8---having a threaded groove 8 the ring member C being formed to define the movement of the cam sleeve 5 in the direction of the optical axis. The zooming operational barrel 8'and the ring member 8---are integrally coupled by a set screw 15. When the ring member C is moved to the infinite distance focussing position without rotation of the cam sleeve 5, the cam sleeve 5 moves in the direction of the optical axis by the action of the threads 4c and 8b, and the lens groups L,, L,[ and L,,, are moved back and forth without variation of the space therebetween. Accordingly, the focussing position may be varied so as to perform a so-called rear adjustment. With the guide groove 8a of the zooming operational barrel 8' co-operating with the guide pin 14 coupled to the cam ring 5 and the zooming operational barrel 8'and the ring member integrally coupled by the set screw 15 after the rear adjustment, the cam sleeve 5 and the divided ring members 8'and W wil rotate integrally. In the preferred embodiment, the defini- tion of the path of movement of the cam sleeve 5 in the direction of the optical axis is achieved through the zooming barrel 8 with the mount barrel 4. Still further, a modification may be employed in which the cam sleeve 5 is moved directly by the mount barrel 4 thereby defining the axial movement thereof.

Upon rotation of the zooming barrel 8 from the minimum focal length setting to the maximum focal length setting, the cam barrel 5 is moved (rotated) from the left to the right as viewed in Figure 3. When the cam sleeve 5 rotates, the guide pin 12 which is engaged with the zooming groove 5a and guide grooves 3a and 4b moves downwardly from the position shown in Figure 3 to the position shown in Figure 4. Simultaneously, the first moving barrel 2 and the second lens group L,, move from the position shown in the upper half to the position shown in the lower half of Figure 1. Also, the guide pin 13, which is engaged with the groove 5c and the guide groove 4a, moves upwardly from the position illustrated in Figure 3 to the position shown in Figure 4, while the second moving barrel 3, the first lens group L, and the third lens group L,,, move from the position shown in the upper half to the position shown in the lower half of Figure 1. Since the guide pin 11 rigidly coupled. to the cam sleeve 5 is engaged with the guide groove 7c formed in the change-over sleeve 7, rotation of the cam sleeve 5 is transmitted directly to the change-over sleeve 7 such that the guide pin 10 slidingly disposed in the guide groove 3dand the projections 7a and 7b are moved from the position shown in Figure 3to that shown in Figure 4. Also, the change-over sleeve 7 is rotated around the optical axis and is moved in the direction of the optical axis in the same manner as the second 3 GB 2 046 469 A 3 1 10 f moving barrel 3 from the position shown in the upper half to the position shown in the lower half of Figure 1, while the guide groove 7c moves along the guide pin 11 upwardly f rom the position shown in Figure 3 to that shown in Figure 4.

Next, when the focussing barrel 1 is rotated from infinite focus to minimum focus, the focussing barrel 1 and the first lens group L, are moved from right to left by the helicoid screw threads la and 3b from the position shown in the lower half of Figure 1 to the position shown in the upper half of Figure 2. Upon rotation of the focussing barrel 1, the guide pin 9 sliclingly disposed in the guide groove lb and the changeover groove 6a moves from the position shown in Figure 4 to the position shown in Figure 5, whereupon the change- over groove 6a confronts to projections 7a. In this position, it is possible to make the change-over to the close-focussing mode.

To execute the change-over into the close- focussing mode, the change-over sleeve 7 is manually moved from right to left as viewed in Figure 2, i.e. it is moved upwardly to the position shown in Figure 5. By this operation, the projection 7a becomes engaged with the change-over groove 6a, the guide pin 11 disengages from the guide groove 7c, and the guide pin 10 engages in the guide groove 3e.

Figure 6 shows the positions of the various members immediately after change-over into the close-focussing mode. Since the guide pin 10 is engaged with the guide groove 3e and the second moving barrel 3 does not move along the optical axis under this condition, rotation of the changeover ring 7 is prevented. Also, since the projection 7a is engaged with the change-over groove 6a, the guide ring 6 is also prevented from rotating. Accordingly, rotation of the focussing barrel 1 is prevented. Moreover, upon disengagement of the guide pin 11 from the groove 7c, the cam ring 5 is prevented by the projection 7b from rotating from right to left as viewed in Figure 6, although it can be rotated from left to right. Thus, the zooming barrel 8 can be rotated freely in the close-focussing mode.

Figure 7 illustrates the position where the zooming barrel 8 has been further rotated from the position shown in Figure 6, i.e. from left to right as viewed in the Figure. When the zooming barrel 8 is moved in this manner, due to the engagement of the guide pin 14 and the guide groove 8a, the cam sleeve 5 moves from left to right in the same manner. In addition, the guide pin 11 moves along an upright surface 7d perpendicular to the optical axis, thereby preventing the change-over sleeve 7 from moving downwardly from the position shown in Figure 7 so that engagement between the change-over groove 6a and the projection 7a is maintained. Thus, except at the precise position of change-over, the change-over operation of the change-over sleeve 7 is prevented.

Also during close-focussing, the guide pin 12 is moved upwardly by the groove 5b from the position shown in Figure 6 to the position shown in Figure 7. This causes the first moving barrel 2 and the second lens group L11 move from right to left towards the position shown in the lower half of Figure 2, which corresponds to the minimum focal distance from close-up photography. Furthermore, the guide pin 13 is maintained in the position shown in Figure 6 by the groove 5d and the guide groove 4a. In the case where the movement of cam sleeve 5 and the zooming barrel 8 in the direction of the optical axis is defined by screw threads, the macro groove 5d must be formed as a lead groove to offset the lead of the screw. However, if the cam sleeve 5 and the zooming barrel 8 are so constructed that they do not move in the direction of the optical axis, the macro groove ' 5d may be formed as a horizontal straight groove, as shown in Figures 3 to 7. Due to the fact that the guide pin 13 does not move in the direction of the optical axis from its position shown in Figure 6 to the position shown in Figure 7, the second moving barrel 3, the first lens group L, and the third lens group L111 do not move during close-focussing of the zoom lens system.

In order to release the lens system from the close-focussing mode, the zooming barrel 8 is moved from right to left as viewed in Figure 7. This causes the cam sleeve 5 to move in the same direction until the guide pin 11 comes into abutment with the projection 7b, as shown in Figure 6. From the position shown in Figure 6, the change-over sleeve 7 is moved downwardly to release the projection 7a from the change- over groove 6a and to disengage the guide pin 10 from the guide groove 3e, after which the guide pin 11 engages with the guide groove 7c as shown in Figure 5. At this point, the lens system has been returned to its normal focussing mode.

A second embodiment of the zoom lens system is shown in Figures 8 and 9, wherein like reference numbers denote similar members as in the previously-described embodiment. In this embodiment, however, the lens system is composed of only two lens groups L, and L11. Zooming is performed by moving the first lens group L, relative to the second lens group L11, and normal focussing is achieved by maintaining the second lens group in a fixed position while moving the first lens group. Close-up focussing can be performed when the lens system is set to its maximum focal length and its minimum focus, and is effected by holding the second lens group in a fixed position L11 and moving the first lens group L1. The upper half of Figure 8 shows the lens system set at its minimum focal length and focussed on infinity, whereas the lower half of this Figure shows the lens system set to its maximum focal length and focussed on infinity. The upper half of Figure 9 shows the lens system set at its maximum focal length and its minimum focal distance ready for change-over into the close-focussing mode, and the lower half of Figure 9 shows the lens system in its close-focussing mode and set to the minimum focussing distance.

The primary distinctions of this embodimentfrom that described previously are thatthe focussing barrel 1 supporting the first lens group L, is threadedly mounted on the first moving barrel 2 by helicoid screw threads la and 2b, the first moving barrel 2 is sliclably supported directly on the mount barrel 4, and the guide ring 6 and the change-over sleeve 7 are co-axially supported on the mount barrel 4. Grooves 9 and 10 defining the rotational 4 GB 2 046 469 A 4 movement of the guide ring 6 and the change-over sleeve 7 respectively are formed in the mount barrel 4. In the earlier described embodiment, such guide grooves are formed in the second mov4ng barrel 3. In operation, the operational direction of the change over sleeve 7 in changing into the close-focussing mode is constrained. That is, the change-over-sleeve 7 moves from the left to the right as viewed in Figures 8 and 9; however, any operational direction may be used.

With this construction, in the same manner as for the zoom lens system composed of three lens groups, when the zooming barrel 8 is rotated from the minimum focal length position, the cam sleeve 5 rotates together therewith, the first lens group L, moves from left to right as viewed in Figure 8 by means of a suitable groove formed in the cam sleeve 5, and the second lens group LI, moves from right to left until it reaches the position shown in the lower half of Figure 8. When in this position the focussing barrel 1 is rotated, the second lens group is held fixed and the first lens group L, moves from right to left to the minimum focus position shown in the upper half of Figure 9. At this point, the change-over groove 6a formed in the guide ring 6 confronts the projection 7a formed in the change-over sleeve 7. When the change-over sleeve 7 is moved from left to right, the projection 7a falls into the change-over groove 6a and the guide pin 10 moves from a guide groove 4e to a guide groove 4f (which correspond respectively to the guide grooves 3d and 3e of the previously described embodiment). Also, rotation of the change-over sleeve 7 is prevented, as are rotation of the guide ring 6 and the focussing barrel 1. Further, the guide pin 11 disengages from the guide groove 7c thereby enabling the cam sleeve 5 to rotate for the close-focussing operation. Therefore, when the zooming barrel 8 is rotated from this position towards the minimum focus position, the second lens group Lil is held stationary by a suitable groove formed in the cam sleeve 5 and the first lens group Ll moves from right to left until it reaches the position shown in the lower half of Figure 9, which corresponds to the minimum close-up photographing distance. To release the lens system from the close-focussing mode, the operational direction of the change-over sleeve is reversed. The other operations of this embodiment are the same as for the zoom lens system composed of three lens groups.

FigureslOandll show a third embodiment of the zoom lens system, which is composed of four lens group L, to Liv. In this embodiment, zooming is carried out by maintaining the first and fourth lens groups L, and Llv at constant positions and moving the second and third lens groups Lil and Lill relative to one another. Normal focussing is carried out by moving onlythe first lens group Ll, while closefocussing is carried out by moving only the second lens group Lil when the lens system is set to its minimum focussing distance and its maximum focal length. In Figures 10 and 11, like reference numerals are used to designate similar members to those used in the zoom lens system composed of three lens groups. The upper half of Figure 10 shows the lens system set to its minimum focal length and focussed on infinity, while the lower half of this Figure shows the lens system set to its maximum focal length and focussed on infinity. The upper half of Figure 11 illustrates the lens system set to its maximum focal length and its minimum focus ready for closefocussing operation, and the lower half of this Figure shows the lens system atthe minimum focus setting in its close-focussing mode.

The zoom lens system of Figures 10 and 11 differs from that described above in relation to Figures 1 to 7 in the following main respects. The focussing barrel 1 is supported on the mount barrel 4 by threaded engagement between helicoid screw threads la and 4d; the first moving barrel 2 is slidingly supported directly on the mount barrel 4; and the guide ring 6 and the change-over sleeve 7 are supported on the mount barrel 4. With this construction, in the same manner as for the firstdescribed zoom lens system composed of three lens groups, by rotating the zooming barrel 8 from the position shown in the upper half of Figure 10 the cam sleeve 5 is rotated and, by means of suitable grooves formed therein, causes the first lens group Ll and the fourth lens group Llvto be maintained at constant positions while the second lens group 1-11 is moved from left to right and the third lens group 1-111 is moved from right to left until they reach the position shown in the lower half of Figure 10. When, under this condition, the focussing barrel 1 is rotated to the minimum focussing distance position, the change-over groove 6a formed in the guide ring 6 comes into alignment with the projection 7a on the change- over sleeve 7, whereupon the lens system is in the position shown in the upper half of Figure 11. When the change- over sleeve 7 is moved from right to left, the change-over groove 6a receives the projection 7a and the guide pin 10 disengages from a guide groove 4e and engages with a guide groove 4f.

The guide grooves 4e and 4f correspond respectively to the grooves 3d and 3e in the first-described embodiment. At this point, rotation of the changeover sleeve 7 is prevented as is rotation of the guide ring 6 and the focussing barrel 1. At the same time, the guide pin 11 disengages from the guide groove 7c enabling the cam sleeve to rotate to the close-up photographing region. Further, when the zooming barrel 8 is rotated from this position, the cam sleeve 5 rotates therewith and causes the second lens group 1-11 only to move from right to left by means of a suitable groove formed therein, thereby effecting close-focussing. Release of the lens system from the close-focussing mode is achieve by the same operation as in the first-described embodiment.

As described above in more detail, movement of the lens groups is controlled by the cam sleeve 5, the change-over sleeve 7 which conveys the rotational position of the cam sleeve 5, and the guide ring 6 which conveys the rotational position of the focus- sing barrel 1. Rotation of the focussing barrel 1 after change-over to the close-focussing mode is impossible, and the rotational limits for the zooming barrel 8 are changed from the zooming region to the closefocussing region. Accordingly, it is possible to provide a scale (not shown) for close-up photo- GB 2 046 469 A 5 graphing in addition to a zooming scale (not shown) on the zooming barrel 8 for assisting in the photographing operation. Further, when the zooming barrel 8 is positioned in the close-up photographing region, the change-over sleeve 7 cannot be moved beyond the close-up photographing region and, since the focussing barrel 1 cannotthen be rotated, operational errors are minimised or eliminated.

In the specific embodiments described, changeover to the close-focussing is possible when the lens system is set to the minimum focussing distance and the maximum focal length. However, since the exchange of the changeover information for the close-focussing mode is carried out through the guide ring 6 in co-operation with the focussing barrel 1 and the changeover sleeve 7 in co-operation with the cam sleeve 5,.proper operation in this mode is set by the relationship between the change-over groove 6a and the projection 7a. It is, of course, possible to apply the teachings of the invention to any zoom lens system which includes provision for close-focussing.

Claims (18)

1. A zoom lens system operable in a normal focussing mode and a closefocussing mode, comprising a focussing ring rotatable to effect focussing of the lens system in the normal focussing mode, a zooming ring rotatable independently of the focussing ring to alter the focal length of the lens system in the normal focussing mode and to effect closefocussing of the lens system in the close-focussing mode, and a change-over control operable to change the lens system between its normal focussing and close-focussing modes only when the focussing ring and the zooming ring are both in respective predetermined positions, operation of the control into the close- focussing mode rendering the focussing ring inoperative.

2. A zoom lens system as claimed in claim 1, wherein operation of the change-over control into the close-focussing mode locks the focussing ring against rotation relative to a fixed mount of the lens system.

3. Azoom lens system as claimed in claim 1 or 2, wherein the change-over control includes a changeover member which is rotatable with the zooming ring in the normal focussing mode and which is held against such rotation in the close-focussing mode, change-over between the normal focussing and close-focussing mode being effected by movement of the change-over member axially of the lens system.

4. A zoom lens system as claimed in claim 3, wherein first interlock means prevents the changeover member from being moved axially unless the change-over member is in a predetermined angular position with respect to a fixed mount of the lens system, and second interlock means prevents the change-over member from being moved axially unless the change-over member and the focussing ring are in predetermined relative angular positions.

5. A zoom lens system as claimed in claim 4, wherein the second interlock means includes a slot in a guide ring which is fixed for rotation with the focussing ring and a projection on the change-over member which is aligned with the slot to permit said axial movement of the change-over member only when the change-over member and the focussing ring are in said predetermined relative angular positions.

6. Azoorn lens system as claimed in claim 4or5, wherein third interlock means prevents the change- over member from being moved out of its axial position corresponding to the close-focussing mode of the lens system unless the zooming ring is in said predetermined angular position with respect to the fixed mount.

7. A zoom lens system as claimed in claim 6, wherein the third interlock means includes an abutment which is movable with the zooming ring and a surface on the change-over member which is perpendicular to the axis of the lens system, the abutment being in sliding engagement with said surface when the zooming ring is rotated to effect focussing in the close-focussing mode.

8. A zoom lens system as claimed in claim 7, wherein the change-over member can be moved axially only when the zooming ring is in an angular position corresponding to one end of the zooming range in the normal focussing mode, and in the close-focussing mode a stop on the change-over member engagement said abutment to prevent rotation of the zooming ring out of said angular position in a direction corresponding to its zooming movement in the normal focussing mode.

9. Azoorn lens system as claimed in claim 7 or8, wherein in the normal focussing mode the change- over member is coupled to the zooming ring for rotation therewith by means of an axial slot in the change-over member in which said abutment engages.

10. Azoorn lens system as claimed in anyone of claims 3 to 9, wherein a cam sleeve is rotatable with the zooming ring and determines the relative positions of lens groups of the lens system during zooming in the normal focussing mode and during focussing in the close-focussing mode, and the change-over member is coupled to the zooming ring for rotation therewith in the normal focussing mode through the intermediary of the cam sleeve.

11. A zoom lens system as claimed in any preceding claim, wherein the zooming ring moves axially of the lens system as it is rotated, and a cam sleeve which determines the relative positions of lens groups of the lens system during zooming in the normal focussing mode and during focussing in the close-focussing mode is moved axially of the lens system with the zooming ring.

12. A zoom lens system as claimed in claim 3, wherein movement of the change-over member out of its position corresponding to the closefocussing mode during rotation of the zooming ring is pre- vented by engagement of an abutment movable with the zooming ring with a surface perpendicular to the axis of the lens system, said surface being formed on the change-over member or the focussing ring.

13, A zoom lens system comprising:

6 GB 2 046 469 A first, second and third lens groups; a focussing barrel supporting the first lens group and having a helicoid screw formed on an inner portion thereof and a first guide groove for transmit- ting angular movement of the focussing barrel during rotation thereof; a first moving barrel supporting the second lens group and having a first guide pin rigidly coupled thereto; a second moving barrel supporting the third lens group and slidingly supporting the first moving barrel, the second moving barrel having a helicoid screw thread meshing with the helicoid screw thread of the focussing barrel, a second guide pin rigidly coupled thereto, a second guide groove extending parallel to the optical axis of the lens system and having disposed therein the first guide pin for defining the path of rotational movement of the first moving barrel about the optical axis, a third guide groove extending perpendicular to the optical axis for defining the range of focussing of the lens system, and fourth and fifth guide grooves for defining the zooming range of the lens system, the fourth guide groove extending perpendicularly to the optical axis and the fifth guide groove extending from an end portion of the fourth guide grooves parallel to the optical axis, the fifth guide groove being substantially shorter than the fourth guide groove; a fixed mount barrel slidably supporting the second moving barrel, and having a sixth guide groove which extends parallel to the optical axis, and in which the second guide pin is slidingly disposed, the sixth guide groove defining the path of rotational movement of the second moving barrel around the optical axis and guiding the second moving barrel in the direction of the optical axis, and a seventh guide groove which extends parallel to the optical axis and in which the first guide pin is slidingly disposed; a cam sleeve siidingly supported by the mount barrel and having third and fourth guide pins rigidly coupled thereto, the cam sleeve having formed therein eighth and ninth guide grooves for imparting relative movement to the second and third lens groups respectively during zooming and tenth and eleventh guide grooves for imparting relative movement to the second and third lens groups respectively during close- focussing, the eighth and tenth guide grooves being joined at end portions thereof such that the eighth guide groove extends forwardly from itsjuncture with the tenth guide Rroove at a first pre-determined angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such that the ninth guide groove extends rearwardly from its juncture with the eleventh guide groove substantially parallel to the tenth guide groove, the eleventh guide groove being substantially perpendicularto the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move 6 along the ninth and eleventh guide grooves; a guide ring slidingly supported by the second moving barrel and having a fifth guide pin rigidly coupled tliereto and slidingly disposed in the first and third guide grooves, the guide ring having a changeover groove formed at a position for conveying information as to when a change-ovpr is possible into close-focussing mode; a change-over sleeve slidingly supported bythe second moving barrel and having fixed thereto a sixth guide pin which is slidingly disposed to move in the fourth and fifth guide grooves, the changeover sleeve also having a twelfth guide groove which extends parallel. to the optical axis and in which is slidingly disposed the third guide pin, a first projection which produces an indication for enabling change-over from zooming to close- focussing and a second projection which is disposed so as to indicate a position at which change-over from close- focussing to zooming is possible; and a zooming sleeve having a thirteenth guide groove extending perpendicularly to the optical axis with the fourth guide pin slidingly disposed tHerein wherein, the zooming sleeve being rotatable integ- rally with the cam sleeve.

14. A zoom lens system as claimed in claim 13, wherein the zooming sleeve is rotatably supported by the mount barrel and is freely rotatable around the optical axis.

15. A zoom lens system as claimed in claim 13, wherein the mount barrel has a screw thread, and the zooming sleeve has a corresponding screw thread which is engaged with the screw thread of the mount barrel.

16. A zoom lens system as claimed in claim 13, wherein the mount barrel has a screw thread, and the zooming sleeve comprises a zooming operation al barrel rotatable integrally with the cam sleeve and a ring member having a threaded groove engaged with the screwthread of the mount barrel, the ring member being formed to define movement of the cam sleeve in the direction of the optical axis, the zooming operational barrel and the ring member being coupled to move integrally with one another.

17. A zoom lens system comprising:

first and second lens groups; a focussing barrel supporting the first lens group and having a helicoid screw thread formed on an inner portion thereof and a first guide groove for transmitting angular movement of the focussing barrel during rotation thereof; a first moving barrel having a first guide pin rigidly coupled thereto and also having a helicoid screw thread meshing with the helicoid screwthread of the focussing barrel; a second moving barrel supporting the second lens group and having a second guide pin rigidly coupled thereto; a fixed mount barrel slidingly supporting the first and second moving barrels on inner portions thereof, the mount barrel having therein a second guide groove which extends parallel to the optical axis of the lens system and in which the first guide pin is slidingly disposed, a third guide groove which extends parallel to the optical axis and in which the il 1 1 7 GB 2 046 469 A 7 second guide pin is slidingly disposed, a fourth guide groove which is formed in a rear portion of the mount barrel and which extends perpendicularly to the optical axis, a fifth guide groove for defining a 6 focussing range which extends perpendicularly to the optical axis and an outer co-axial portion of the mount barrel, a sixth guide groove for defining a zooming range which extends perpendicularly to the optical axis in said outer co-axial portion, and a seventh guide groove extending parallel to the optical axis from an end portion of the sixth guide groove; a zooming sleeve positioned around the fourth guide groove; a cam sleeve slidingly supported bythe mount barrel and having third and fourth guide pins rigidly coupledthereto, the cam sleeve also having formed therein eighth and ninth guide grooves for imparting relative movement to the first moving barrel and the second lens group respectively during zooming, and tenth and eleventh guide grooves for imparting relative movement to the first moving barrel and the second lens group respectively during close focussing, the eighth and tenth guide grooves being joined at end portions thereof such that the eighth guide groove extends forwardly from its juncture with the tenth guide groove at a first predetermined angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such thatthe ninth guide groove extends rearwardly of its juncture with the eleventh guide groove substantially parallel to the tenth guide groove, the 100 eleventh guide groove being substantially perpendi cularto the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move along the ninth and eleventh guide grooves, the fourth guide pin being slidingly disposed in the fourth guide groove and being coupled to the zooming sleeve; a guide ring co-axially supported by the mount barrel and having a fifth guide pin rigidly coupled thereto and slidingly disposed in the fifth guide groove, the guide ring having a change-over groove formed at a position for conveying information as to when a change-over is possible into close-focussing mode; and a change-over sleeve co-axially supported bythe mount barrel and having a sixth guide pin fixedly coupled thereto and slidingly disposed in the sixth guide groove, a twelfth guide groove which extends parallel to the optical axis and in which is slidingly 120 disposed the third guide pin, a first projection producing an indication for enabling said change over from zooming to close-focussing and a second projection disposed so as to indicate a position at which change-over from close-focussing to zooming 125 is possible.

18. A zoom lens system comprising; first, second, third and fourth lens groups; a focussing barrel supporting the first lens group and having a helicoid screw thread formed on an inner portion thereof and a first guide groove for transmitting angular movement of the focussing barrel during rotation thereof; a first moving barrel supporting the second lens group and having a first guide pin rigidly coupled thereto; a second moving barrel supporting the third lens group and having a second guide pin rigidly coupled thereto; a fixed mount barrel supporting the fourth lens group and sliclingly supporting the first and second moving barrels on inner portions thereof, the mount barrel having a helicoid screwthread which meshes with the helicoid screw thread of the focussing barrel, a second guide groove which extends parallel to the optical axis of the lens system and in which the first guide pin is slidingly disposed, a third guide groove which extends parallel to the optical axis, a fourth guide groove which is formed in a rear portion of the mount barrel and which extends perpendicularly to the optical axis, a fifth guide groove for defining a focussing range which extends perpendicularly to the optical axis in an outer co-axial portion of the mount barrel, a sixth guide groove for defining a zooming range which extends perpendicularly to the optical axis in said outer co-axial portion, and a seventh guide groove which extends parallel to the optical axis from an end portion of the sixth guide groove, a zooming sleeve positioned around the third guide groove; a cam sleeve slidingly supported by the mount barrel ind having third and fourth guide pins rigidly coupled thereto, the cam sleeve also having formed therein eighth and ninth guide grooves for imparting relati ve movement to the first moving barrel and the second lens group respectively Ouring zooming, and tenth and eleventh guide grooves for imparting relative movement to the first moving barrel and the second lens group respectively during closefocussing, the eighth and tenth guidegrooves being joined at end portions thereof such that the eighth guide groove extends forwardly from its juncture with the tenth guide groove at a first predetermined angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such that the ninth guide groove extends rearwardly of its juncture with the eleventh guide groove the eleventh guide groove being substantially perpendicularto the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move along the ninth and eleventh guide grooves, the fourth guide pin being slidingly disposed in the fourth guide groove and GB 2 046 469 A being coupled to the zooming sleeve; a guide ring co-axially supported by the mount barrel and having a fifth guide pin rigidly coupled thereto and slidingly disposed in the fifth guide groove, the guide ring also having a change-over groove formed at a position for conveying information as to when a change-over is possible into close-focussing mode; and a change-over sleeve co-axially supported by the mount barrel and having a sixth guide pin fixed thereto and slidingly disposed in the sixth guide groove, a twelfth guide groove which extends parallel to the optical axis and in which is slidingly disposed the third guide pin, a first projection producing an indication for enabling said changeover from zooming to close-focussing, and a second projection disposed so as to indicate a position at which change-over from close-focussing to zooming is possible.

Printed for Her Majesty's Stationery Office by Croydon Printing Company Limited, Croydon Surrey, 1980. Published by the Patent Office, 25 Southampton Buildings, London,WC2A lAY, from which copies may be obtained.

T

18. A zoom lens system comprising; first, second, third and fourth lens groups; a focussing barrel supporting the first lens group and having a helicoid screw thread formed on an 130 inner portion thereof and a first guide groove for transmitting angular movement of the focussing barrel during rotation thereof; a first moving barrel supporting the second lens group and having a first guide pin rigidly coupled thereto; a second moving barrel supporting the third ' lens group and having a second guide pin rigidly coupled thereto; a fixed mount barrel supporting the fourth lens groups and slidingly supporting the first and second moving barrels on inner portions thereof, the mount barrel having a helicoid screwthread which meshes with the helicoid screw thread of the focussing barrel, a second guide groove which extends parallel to the optical axis of the lens system and in which the first guide pin is slidingly disposed, a third guide groove which extends parallel to the optical axis, a fourth guide groove which is formed in a rear portion of the mount barrel and which extends perpendicularly to the optical axis, a fifth guide groove for defining a focussing range which extends perpendicularly to the optical axis in an outer co-axial portion of the mount barrel, a sixth guide groove for defining a zooming range which extends perpendicularly to the optical axis in said outer co-axial portion, and a seventh guide groove which extends parallel to the optical axis from an end portion of the sixth guide groove; a zooming sleeve positioned around the third guide groove; a cam sleeve slidingly supported by the mount barrel and having third and fourth guide pins rigidly coupled thereto, the cam sleeve also having formed therein eighth and ninth guide grooves for imparting relative movement to the first moving barrel and the second lens group respectively during zooming, and tenth and eleventh guide grooves for imparting relative movement to the first moving barrel and.the second lens group respectively during closefocussing, the eighth and tenth guide grooves being joined at end portions thereof such that the eighth guide groove extends forwardly f rom its juncture with the tenth guide groove at a first predetermined angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such that the ninth guide groove extends rearwardly of its juncture with the eleventh guide groove substantially parallel to the tenth guide groove, the eleventh guide groove being substantially perpendicular to the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move along the ninth and eleventh guide grooves, the fourth 4uide pin being slidingly disposed in the fourth guide groove and being coupled to the zooming sleeve; a guide ring co-axially supported by the mount barrel and having a fifth guide pin rigidly coupled thereto and slidingly disposed in the fifth guide groove, the guide ring also having a change-over groove formed at a position for conveying informa- 8 GB 2 046 469 A 8 tion as to when a change-over is possible into close-focussing mode. and a change-over sleeve co-axially supported by the mount barrel and having a sixth guide pin fixed thereto and slidingly disposed in the sixth guide groove, a twelfth guide groove which extends parallel to the optical axis and in which is slidingly disposed the third guide pin, a first projection producing an indication for enabling said change- over from zooming to close-focussing, and a second projection disposed so as to indicate a position at which change-over from close-focussing to zooming is possible.

19. A zoom lens system substantially as hereinb efore described with reference to Figures 1 to 7, or Figures 8 and 9, or Figures 10 and 11 of the accompanying drawings.

20. A zoom lens system substantially as hereinb efore described with reference to Figures 1 to 7 as modified by either of Figures 12 and 13 of the 85 accompanying drawings.

New claims or amendments to claims filed on 13 August 1980 Superseded claims 13,17 and 18 New or amended claims:- 13. A zoom lens system comprising: first, second and third lens groups; a focussing barrel supporting the first lens group and having a helicoid screw thread formed on an inner portion thereof and a first guide groove for transmitting angular movement of the focussing barrel during rotation thereof; a first moving barrel supporting the second lens 100 group and having a first guide pin rigidly coupled thereto; a second moving barrel supporting the third lens group and slidingly supporting the first moving barrel, the second moving barrel having a helicoid screw thread meshing with the helicoid screw thread of the focussing barrel, a second guide pin rigidly coupled thereto, a second guide groove extending parallel to the optical axis of the lens system and having disposed therein the first guide pin for defining the path of rotational movement of the first moving barrel about the optical axis, a third guide groove extending perpendicularly to the optical axis for defining the range of focussing of the lens system, and fourth and fifth guide grooves for 115 defining the zooming range of the lens system, the fourth guide groove extending-perpendicularly to the optical axis and the fifth guide groove extending from an end portion of the fourth guide grooves parallel to the optical axis, the fifth guide groove being substantially shorter than the fourth guide groove; a fixed mount barrel slidably supporting the second moving barrel, and having a sixth guide groove which extends parallel to the optical axis, and in which the second guide pin is slidingly disposed, the sixth guide groove defining the path of rotational movement of the second moving barrel around the optical axis and guiding the second moving barrel in the direction of the optical axis, and 130 a seventh guide groove which extends parallel to the optical axis and in which the first guide pin is slidingly disposed; a cam sleeve slidingly supported by the mount barrel and having third and fourth guide pins rigidly coupled thereto, the cam sleeve having formed therein eighth and ninth guide grooves for imparting relative movement to the second and third lens groups respectively during zooming and tenth and eleventh guide grooves for imparting relative movement to the second and third lens groups respectively during close-focussing, the eighth and tenth guide grooves being joined at end portions thereof such that the eighth guide groove extends forwardly from its juncture with the tenth guide groove at a first predetermined angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such that the ninth guide groove extends rearwardlyfrom its juncture with the eleventh guide groove, the eleventh guide groove being substantially perpendicularto the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move along the ninth and eleventh guide grooves; a guide ring slidingly supported by the second moving barrel and having a fifth guide pin rigidly coupled thereto and slidingly disposed in the first and third guide grooves, the guide ring having a change-over groove formed at a position for conveying information as to when a change-over is possible into close-focussing mode; a change-over sleeve slidingly supported bythe second moving barrel and having fixed thereto a sixth guide pin which is slidingly disposed to move in the fourth and fifth guide grooves, the change- over sleeve also having a twelfth guide groove which extends parallel to the optical axis and in which is slidingly disposed the third guide pin, a first projection which produces an indication for enabling change-over from zooming to close-focussing and a second projection which is disposed so as to indicate a position at which change-over from closefocussing to zooming is possible; and a zooming sleeve having a thirteenth guide groove extending perpendicularly to the optical axis with the fourth guide pin slidingly disposed therein wherein, the zooming sleeve being rotatable integrally with the cam sleeve. 17. A zoom lens system comprising: first and second lens groups; a focussing barrel supporting the first lens group and having a helicoid screw thread formed on an inner portion thereof and a first guide groove for transmitting angular movement of the focussing barrel during rotation thereof; a first moving barrel having a first guide pin rigidly coupled thereto and also having a helicoid screw thread meshing with the helicoid screw thread of the focussing barrel; a second moving barrel supporting the second lens group and having a second guide pin rigidly P 9 GB 2 046 469 A 9 coupled thereto; a fixed mount barrel slidingly supporting the first and second moving barrels on inner portions there of, the mount barrel having therein a second guide groove which extends parallel to the optical axis of the lens system and in which the first guide pin is sliclingly disposed, a third guide groove which extends parallel to the optical axis and in which the second guide pin is slidingly disposed, a fourth guide groove which is formed in a rear portion of the mount barrel and which extends perpendicularly to the optical axis, a fifth guide groove for defining a focussing range which extends perpendicularly to the optical axis in an outer co-axial portion of the mount barrel, a sixth guide groove for defining a zooming range which extends perpendicularly to the optical axis in said outer co-axial portion, and a seventh guide groove extending parallel to the optical axis from an end portion of the sixth guide groove; a zooming sleeve positioned around the fourth guide groove; a cam sleeve slidingly supported by the mount barrel and having third and fourth guide pins rigidly coupled thereto, the cam sleeve also having formed therein eighth and ninth guide grooves for imparting relative movement to the first moving barrel and the second lens group respectively during zooming, and tenth and eleventh guide grooves for imparting relative movement to the first moving barrel and the - 95 second lens group respectively during close focussing, the eighth and tenth guide grooves being joined at end portions thereof such that the eighth guide groove extends forwardly from its juncture with the tenth guide groove at a first predetermined 100 angle with respect to the optical axis and such that the tenth guide groove extends forwardly from said juncture at a second predetermined angle with respect to the optical axis, the ninth and eleventh guide grooves being joined at end portions thereof such that the ninth guide groove extends rearwardly of its juncture with the eleventh guide groove, the eleventh guide groove being substantially perpendi cular to the optical axis, the first guide pin being slidingly disposed to move along the eighth and tenth guide grooves and the second guide pin being slidingly disposed to move along the ninth and eleventh guide grooves, the fourth guide pin being slidingly disposed in the fourth guide groove and being coupled to the zooming sleeve; a guide ring co-axially supported by the mount barrel and having a fifth guide pin rigidly coupled thereto and sliclingly disposed in the fifth guide groove, the guide ring having a change-over groove formed at a position for conveying information as to 120 when a change-over is possible into close-focussing mode; and a change-over sleeve co-axially supported bythe mount barrel and having a sixth guide pin fixedly coupled thereto and slidingly disposed in the sixth guide groove, a twelfth guide groove which extends parallel to the optical axis and in which is slidingly disposed the third guide pin, a first projection producing an indication for enabling said change over from zooming to close-focussing and a second projection disposed so as to indicate a position at which change-over from close-focussing to zooming is possible.